Abstract : In this paper, we explore three issues related to the acquisition of mood selection in Spanish relative clauses by second language (L2) and heritage (HL) speakers of Spanish: (1) whether HL speakers are more native-like than L2 learners; (2) whether the speakers’ performance differs depending on task modality (written vs. oral), since HL speakers are known to perform better in oral tasks and L2 learners tend to do better in written tasks; and (3) whether knowledge of French as an L1/dominant language (DL) has an impact on the acquisition of Spanish subjunctive, since both languages include this mood in their grammars, but it is used more productively in Spanish. Results from a sentence combination felicity task (SCFT) in Spanish—in written and oral forms—and a written elicited production task (EPT) in French, administered to advanced L2 and HL speakers of Spanish whose L1/DL is French and two monolingual (Spanish and French) control groups, revealed that L2 learners pattern more closely with the control group than HL speakers in the SCFT, both written and orally. In the EPT, all bilingual speakers display higher levels of subjunctive use than the control group, showing a potential influence from the L2/weaker language on the L1/DL.